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| United States Patent |
6,109,166
|
|
Granberg
|
August 29, 2000
|
Fluid pressure cylinder
Abstract
Pressure fluid cylinder including a slot type cylinder tube which is
shielded and sealed by an outer (11) and an inner (10) sealing band, a
piston (2,5) which is arranged inside the tube and a transfer means (3)
for transferring the movement of the piston to the outside of the cylinder
tube. The invention is distinguished by the piston comprising a central
body (2) and two piston end units (5) which surround the respective end
thereof and support directly against the body, said units comprising guide
elements (17) for the piston inside the cylinder, and by each piston end
unit (5) comprising an integral piston sealing member seat (7).
| Inventors:
|
Granberg; Rune (Alvajo, SE)
|
| Assignee:
|
AB Rexroth Mecman (Stockholm, SE)
|
| Appl. No.:
|
181937 |
| Filed:
|
October 28, 1998 |
Foreign Application Priority Data
| Current U.S. Class: |
92/88 |
| Intern'l Class: |
F01B 029/00 |
| Field of Search: |
92/88,128
|
References Cited
U.S. Patent Documents
| Re33637 | Jul., 1991 | Hoglund | 92/88.
|
| 4373427 | Feb., 1983 | Garlapaty et al.
| |
| 4519297 | May., 1985 | Lipinski et al. | 92/88.
|
| 4519397 | May., 1985 | Lipinski | 92/88.
|
| 4545290 | Oct., 1985 | Lieberman | 92/88.
|
| 4555980 | Dec., 1985 | Hoglund | 92/88.
|
| 4664019 | May., 1987 | Lipinski et al. | 92/88.
|
| 4685383 | Aug., 1987 | Ruchser | 92/88.
|
| 4724744 | Feb., 1988 | Rosengren | 92/88.
|
| 5040332 | Aug., 1991 | Aquilina | 92/88.
|
| 5473971 | Dec., 1995 | Takeuchi et al. | 92/88.
|
| 5988042 | Nov., 1999 | Lamle | 92/88.
|
| 6007247 | Dec., 1999 | Rosengren et al. | 92/88.
|
| Foreign Patent Documents |
| WO 95/18322 | Jul., 1995 | WO.
| |
Primary Examiner: Ryznic; John E.
Attorney, Agent or Firm: Townsend & Townsend & Crew LLP
Claims
What is claimed is:
1. Pressure fluid cylinder of the kind including a slot type cylinder tube
which is shielded and sealed by an outer (11) and an inner (10) sealing
band, a piston (2,5) which is arranged moveable inside the tube and a
transfer means (3) for transferring the movement of the piston through the
slot to the outside of the cylinder tube, whereby the piston on each
piston end comprises on the one hand a seat (7) for a piston sealing
member (6) and on the other hand upper (14) and lower (13,15) guide means
for co-operation with said outer and inner sealing bands, characterized in
that the piston comprises a central body (2) and two piston end units (5)
which surround the respective end thereof and support directly against the
body, said units comprising guide elements (17) for the piston inside the
cylinder, and that each piston end unit (5) comprises an integral piston
sealing member seat (7).
2. Cylinder according to claim 1, characterized in that the seat (7) for
the piston sealing member (6) is comprised of a groove on an axially
extending portion having reduced dimensions in radial directions.
3. Cylinder according to claim 1, characterized in that each piston end
unit (5) includes integral upper and lower guiding elements (13,14,15) for
the sealing bands (10,11).
4. Cylinder according to claim 3, characterized in that the guide for the
inner band (10) is comprised of two rounded guiding surfaces (13,15), each
being arranged to cooperate with one side of said band.
5. Cylinder according to claim 3, characterized in that the guide for the
outer band (11) is comprised of a guiding surface (14) on a guiding tongue
(12) which is adapted for penetrating the cylinder slot.
6. Cylinder according to claim 1, characterized in that each piston end
unit (5) comprises an integral cushioning projection (8).
7. Cylinder according to claim 1, characterized in that the piston end unit
(5) is produced from a synthetic material.
8. Cylinder according to claim 1, characterized in that the piston body
(2), the transfer means (3) and a fastening portion in the form of a
shuttle superstructure (4) being moveable on the outside of the cylinder,
together form an integral piston unit.
9. Cylinder according to claim 8, characterized in that the piston unit is
comprised of an extruded profile body.
10. Cylinder according to claim 1, characterized in that the piston end
unit (5) comprises a snap lock means (16) which is adapted to co-operate
fixingly with snap lock recess means in the piston body (2) for locking
the piston end unit thereto.
11. Cylinder according to claim 1, characterized in that the piston end
unit (5) is guided against rotation relative to the piston body by means
of an element carrying an inner guiding surface (15) for the inner sealing
band (10).
Description
This invention concerns a fluid pressure cylinder according to the preamble
of claim 1.
U.S. Pat. No. 4,555,980 (AB Mecman) discloses a fluid pressure cylinder of
this kind, wherein the piston at each end portion on its body comprises a
groove for receiving a collar type piston sealing member, and inside the
seal, a guiding sleeve, preferably of polyamide so as to guide the piston
movement inside the cylinder tube. The outer and the inner sealing band
guides are comprised of guiding elements which are mounted separately on
the piston body which in turn is connected to a separate shuttle carriage
which is moveable on the outside of the cylinder tube.
The construction of the piston device of the disclosed fluid pressure
cylinder is thus complicated and presupposes several machining operations
and considerable assembly work to produce. All together this results in a
fluid pressure cylinder which is costly to produce and therefore is
relatively expensive.
In other previously known fluid pressure cylinders, the piston comprises
piston end units which either are partly inserted into the tubular piston
body or are attached to the axial outside of the body by separate
connecting rods. These arrangements are complicated as well and also
unsafe with respect to strength.
It is an aim of this invention to provide a development of the known art
which does not suffer from the mentioned drawbacks and thus is possible to
produce at a low cost, provides advantageous force reception and further
is suitable for manufacture in large series.
This aim is obtained in a flow pressure cylinder of the above mentioned
kind by the features of the characterizing portion of claim 1.
By thus each piston end unit surrounding an end of the piston body so that
is comprises a guide element for the piston, several advantages are
obtained. Firstly, the piston body may be manufactured essentially more
rationally, since essential piston functions are provided by the piston
end units. By these units in an integral manner including the piston guide
elements and the seat for the sealing member, the process of manufacture
is also simplified and, not least, essentially the assembly work,
resulting in a fluid pressure cylinder which may be manufactured at
essentially lower costs than before. At the same time a solution is
provided which is advantageous from the aspects of force distribution and
strength.
Claim 2 defines a construction of the seat for the piston seal member which
is preferred with respect to manufacture.
The aspect of the invention according to claim 3, wherein the band guiding
means are integral with the piston end units, result in further advantages
with respect to manufacture. According to the known art these elements are
made of separate parts which are mounted separately on the piston and on
the transfer member respectively. By the present aspect, the number of
elements included in the device may thus be radically reduced and the
assembly work simplified. Claims 4 and 5 define preferred embodiments of
the elements concerned.
The feature of claim 6 provides further advantages of the device in the
case where the cushioning projection is arranged on the piston which
further brings about the advantage that drawing of channels in the
cylinder end walls may be made more simple and with less flow
restrictions.
The feature according to claim 8 result in a preferred simplification of
the piston construction, which is essentially accentuated by the feature
in claim 9 which allows manufacture of the piston unit to be simplified so
that the entire piston unit including the piston body, the transfer means
and the shuttle superstructure is manufactured as a part of a profile body
of extruded aluminium, preferably, or an aluminium alloy. Machining of the
profile body is essentially limited to cutting and a few machining
operations in order to achieve access to passage channels for the sealing
bands.
The feature in claims 10 and in 11 assure further simplified assembly and
safe fastening.
The invention will now be described in more detail at the background of an
embodiment and with reference to the annexed drawings, wherein:
FIG. 1 shows a section through a piston unit according to the invention
with mounted piston end units,
FIG. 2 shows a piston end unit according to the invention in a perspective
view, and
FIG. 3 shows the piston end unit of FIG. 2 in an end view as seen in the
direction of arrow III.
In FIG. 1, 1 indicates a piston unit including an essentially tubular
piston body 2 a transfer means 3 for penetration through the cylinder slot
and a shuttle superstructure 4. A piston end unit 5 is fitted on each
axially most outward end part of the piston body and is comprising a
partially sleeve-shaped portion 5' (is more clear on FIG. 2) for
surrounding a respective piston body end, and further, axially in the
direction from said portion 5', a projecting part having radially reduced
dimensions which forms a seat 7 for a piston sealing member 6. Most
outwardly on the unit 5 there is provided a cushioning projection 8 for
cushioning co-operation with a corresponding recess in the cylinder end
wall and, sideways with respect to the cushioning projection 8, buffer
devices 9 for cushioning the strike against the cylinder end wall.
10 indicates an inner sealing band which is not shown in detail, and 11 an
outer sealing band which both may be of a conventional type. The sealing
bands 10 and 11 run in a channel 2' in the piston body and in a channel 4'
in the shuttle super-structure respectively. In the shown embodiment, the
piston end unit 5 carries a band guiding element 12 which on the one hand
comprises an inner guiding surface 13 for co-operation with the upper
surface of the inner sealing band, on the other hand an outer guiding
surface 14 on a guiding tongue extending through the cylinder slot
(illustrated in more detail on FIG. 2) for the co-operation with the outer
sealing band 11. Further, the shuttle superstructure 4 is provided with
depression means 20 which may be of a conventional kind for the
co-operation with the upper side of the outer sealing band 11.
FIG. 1 further shows a snap lock means 16 on each piston end unit, said
means comprising an inclined entering surface, tapering against the
direction of fitting on to the piston body 2 and said means being arranged
to co-operate with a corresponding recess in a surface of the piston body.
The perspective view of FIG. 2 illustrate the piston end unit 5, which in
this case is intended for a piston having an oblong transverse section,
with its integral functions, namely the guide surface 17 which is adapted
to guide the piston aggregate inside the cylinder tube, the axially
extending part forming the seat 7 of a sealing member, the axially most
outwardly positioned cushioning projection 8 and the sideways positioned
buffer devices 9 which may be separate elements inserted into recesses in
the piston end unit or integral parts, possibly from another, preferably
softer, material. Further, the guiding tongue is illustrated which forms
the outer part of the band guiding element 12 and the guiding surface 14
provided thereon, the inner guiding surface 13 and the lower guiding
surface 15.
The end view of FIG. 3 more clearly illustrates the sleeve-shape 5', with
the surface 17. It should be noted that the hollow shape, which is most
clearly illustrated in FIG. 3, brings about that a piston body being
inserted without play into the end unit and being positioned inside the
sleeve portion, will receive good guidance at its movement inside the
cylinder tube. The snap lock means 16 is shown as an inwardly directed
inclined pin being positioned centrally on the lower inner surface.
The invention may be modified within the scope of the annexed claims,
whereby also cylinders having piston end units without band guides or
cushioning projections are included in the protection, although it is
highly preferred that such elements are integrated into the unit. The
fastening means for the piston end units may be constructed differently
than what is shown, for example with snap lock means placed on other
places, with grooves and ridges coming into engagement with each other
etc. Also separate pins may be used.
The form of the respective parts may be modified, for example such that the
piston body is reverse U-shaped in section instead of being tubular.
Materials suitable for the piston end unit are synthetic materials and the
methods of production may be conventional for plastic materials.
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